Sulfur cycle as an electron mediator between carbon and nitrate in a constructed wetland microcosm |
| |
| Authors: | Wenrui Guo Yue Wen Yi Chen Qi Zhou |
| |
| Affiliation: | 1. State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China2. Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China3. Key Laboratory of the Three Gorges Region’s Eco-Environment, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China |
| |
| Abstract: | ? Fe(III) accepted the most electrons from organics, followed by NO3?, SO42?, and O2. ? The electrons accepted by SO42? could be stored in the solid AVS, FeS2-S, and S0. ? The autotrophic denitrification driven by solid S had two-phase characteristics. ? A conceptual model involving electron acceptance, storage, and donation was built. ? S cycle transferred electrons between organics and NO3? with an efficiency of 15%. ![]() A constructed wetland microcosm was employed to investigate the sulfur cycle-mediated electron transfer between carbon and nitrate. Sulfate accepted electrons from organics at the average rate of 0.84 mol/(m3·d) through sulfate reduction, which accounted for 20.0% of the electron input rate. The remainder of the electrons derived from organics were accepted by dissolved oxygen (2.6%), nitrate (26.8%), and iron(III) (39.9%). The sulfide produced from sulfate reduction was transformed into acid-volatile sulfide, pyrite, and elemental sulfur, which were deposited in the substratum, storing electrons in the microcosm at the average rate of 0.52 mol/(m3·d). In the presence of nitrate, the acid-volatile and elemental sulfur were oxidized to sulfate, donating electrons at the average rate of 0.14 mol/(m3·d) and driving autotrophic denitrification at the average rate of 0.30 g N/(m3·d). The overall electron transfer efficiency of the sulfur cycle for autotrophic denitrification was 15.3%. A mass balance assessment indicated that approximately 50% of the input sulfur was discharged from the microcosm, and the remainder was removed through deposition (49%) and plant uptake (1%). Dominant sulfate-reducing (i.e., Desulfovirga, Desulforhopalus, Desulfatitalea, and Desulfatirhabdium) and sulfur-oxidizing bacteria (i.e., Thiohalobacter, Thiobacillus, Sulfuritalea, and Sulfurisoma), which jointly fulfilled a sustainable sulfur cycle, were identified. These results improved understanding of electron transfers among carbon, nitrogen, and sulfur cycles in constructed wetlands, and are of engineering significance. |
| |
| Keywords: | Constructed wetland Sulfur cycle Electron transfer Denitrification |
|
| 点击此处可从《Frontiers of Environmental Science & Engineering》浏览原始摘要信息 |
|
点击此处可从《Frontiers of Environmental Science & Engineering》下载全文 |
|
